A measure of total nonfat body compartments (also called lean body mass). Contains most of the body’s water
Fat-free mass, also called lean body mass, is the total amount of non-fat (lean) parts of the body. It consists of approximately 73% water, 20% protein, 6% mineral and 1% ash. Fat-free mass contains virtually all the body’s water, all the metabolically active tissues, and is the source of all metabolic caloric expenditure. The higher the fat free mass the better
“… we found that fat-free mass was lower and fat mass was higher in acutely ill and chronically ill patients than controls.”
– Journal of American Diet Assoc. 2002;102(7):944-955
The following quote from a 1997 edition of the journal Nutrition summarizes the significance of muscle mass as related to healthy aging:
“… no decline with age is as dramatic or potentially more significant than the decline in lean body mass. In fact, there may be no single feature of age-related decline more striking than the decline in lean body mass in affecting ambulation, mobility, energy intake, overall nutrient intake and status, independence and breathing.”
– Journal of Nutrition 127:990S-991S (1997)